Electric measuring instrument.



A. H. HOYT.

ELECTRIC MEASURING INSTRUMENT.

APPLICATION FILED OCT.18,1907.

Patented Nov. 16, 1909.

ADRIAN H. HOYT, OF PENACOOK, NEW HAMPSHIRE.

ELECTRIC MEASURING INSTRUMENT.

Specification of Letters Patent.

Patented Nov. 16, 1909.

Application filed October 18, 1907. Serial No. 397,964.

To all whom it may concern:

Be it known that T, AnRIAN a citizen of the United States, residing inPenacook, in the county of Merrimack and State of New Hampshire, haveinvented an Improvement in Electric Measuring Instruments, of which thefollowing description, in connection with the accompanying drawings, isa specification, like characters on the drawings representing likeparts.

The present invention relates to an electric measuring instrument and isembodied in an instrument for measuring amperage and voltage, beingespecially intended for use in measuring the current used in ignitionsystems for explosive engines.

The instrument is especially useful for automobiles, and may be arrangedfor attachment to the dash-board with the ammeter and voltmeter dials inview, and a controlling switch connected with the instrument.

The invention relates mainly to the wiring, the instruments themselvesbeing of any suitable or usual construction, the purpose of theinvention being to arrange the circuits so that the amperage or thevolta e, or both, can be read while the current is being used.

In accordance with the invention, the ammeter is in circuit with theprimary coils of the vibrator, while the voltmeter is directly connectedin series with the battery or other source of current, the switch beingso arranged as to short circuit the ammeter when in its normal position,and to open the short circuit and close the circuit through thevoltmeter in another position, there being an intermediate position inwhich the ammeter alone is active.

The drawing is a diagram of the primary circuits of an ignition systemwith the instrument included therein.

In accordance with the invention, the ammeter at and voltmeter I), whichmay be-of anysuitable orusual construction, are permanently connected incircuits from the batteries a, there being two batteries shown,andarranged to be selectively used through the agency of a switch 0 inaccordance with the system usually employed in automobile use.

The ammeter is in a circuit in series with the primary coils of thevibrator, the conductor 1 leading from'the switch 0 to a switch post dfrom which conductors 2 and 3 lead into and out of the ammeter, thecondoctor 3 being connected wi h a switch con- H. Hor r,

tact d which, in turn, is connected by means of a conductor 4: with theprimary coils of the vibrator e. The said primary coils are connectedthrough the timer 7 in the usualof the battery 0,"

way with the negative end a conductor 5 being herein shown to completethe circuit.

The switch member al is provided with a. switch handle (i which isarranged to connect the conductor 1 with the conductor 4, or with aconductor 6 which leads from the switch member (i into thevoltmeter, andthence through a conductor 7 to the negative terminal of the battery 0.

The normal position of the switch member (i as shown in full lines, isin contact with the contact piece d sov that a closed circuit of lowresistance through the conductors 1' and i will short circuit theammeter, so that no current is taken thereby. If it is desired to readthe amperage of the current being used, this short circuit is broken bymoving the switch member (P out of contact with the contact piece (1 theammeter thus being in the circuit previously traced through the primarycoils and timer. This gives the current reading, while the machine is inoperation, and shows how much current is bein drawn through the primarycoils. In this way it is not only useful in observing the amount ofcurrent available at any time during the operation of the machine, butis also available in adjusting the coils, since by turning the en e tobring the successive timer contacts into engagement, the amount ofcurrent drawn through each coil may. be measured and the coil adjustedaccordingly. In order to ascertain thevoltage, the voltmeter may be alsobrought into circuit by movingithe switch member d into contact with thecontact piece 03 which also closes the direct circuit from the batterythrough the switch 0 and the voltmeter. The arrangement of circuits,moreover, is such that the two meter coils can be conveniently arrangedupon a common standard and mounted in any convenient position as, forexample, on the dash board of an automobile, and the desired readingscan be taken at anytime, by manipulating the switch which is accessiblefrom the drivers seat.

Claim.

In an electric measuring device, the combination with a source ofcurrent; of an ammeter and a voltmeter mounted on a standard commonto'both; a circuit leading from said source of current through said am--current and the, ammeter; a switch terminal,

ada ted to be bridged by said switch arm, said switch-terminal beinconnected with the source of current to orm a shunt circuit around theammeter when the switch arm is in contact therewith; and a con ductorleading from the source of current through the voltmeter and terminatinin a switch contact adapted to be engaged y the switch member aforesaid,to complete a circuit through the voltmeter. 5

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

ADRIAN H. HOYT.

Witnesses:

Homer: B. SHERBURNE, ELIZA J. SHERBURN'E.

